Conventionally, a heater, a prober and the like using a substrate made of a metal such as a stainless steel and an aluminum alloy have been employed for a semiconductor producing/examining device including an etching apparatus and a chemical vapor deposition apparatus.
However, such a heater made of a metal has the following problems.
At first, since it is made of a metal, the thickness of the heater plate has to be as thick as about 15 mm. It is because in the case of a thin metal plate, warp and strain and the like are caused due to the thermal expansion attributed to heating and therefore result in break and inclination of a silicon wafer set on the metal plate. However, in the case the heater plate is made thick, there are problems that the heater becomes heavy and bulky.
Further, by changing voltage and electric current to be applied to the resistance heating elements, the temperature of the face for heating (hereinafter, referred to as a heating face) an object to be heated such as a semiconductor wafer or the like is controlled, however due to the thickness of the metal plate, there occurs another problem that the temperature of the heating plate does not follow quickly the change of the voltage and the electric current to result in difficulty of the temperature control.
Therefore, JP Kokai Hei 4-324276 proposes a hot plate wherein a non-oxide ceramic with a high thermal conduction and strength such as an aluminum nitride as a substrate are used and resistance heating elements and conductor-filled through holes made of tungsten are formed thereto and nichrome wires as external terminals welded thereto.
Since such a hot plate employs a ceramic substrate for a semiconductor producing/examining device with a high mechanical strength even at a high temperature, the thickness of the ceramic substrate can be thinned to lessen the thermal capacity. As a result, it is made possible that the temperature of the ceramic substrate quickly follows the change of the voltage and electric current.
Generally, with respect to such a hot plate, a temperature measuring element is attached to the surface of or inside the ceramic substrate, and after the ceramic substrate is attached to a supporting case made of a metal through a heat insulating ring and the like made of resin, metal wires from a thermocouple and conductive wires from a resistance heating element are pulled out to the outside of the supporting case through a plurality of through holes formed respectively in a bottom plate and connected to a control apparatus and the like and thus the temperature of the ceramic substrate is controlled on the basis of the temperature measured by the temperature measuring element.